This invention relates to an improved fluidized bed process for chlorinating titanium-containing material. The invention also relates to a spherical, calcined petroleum coke which can be used in such process.
In commercial fluidized bed processes for chlorinating titanium-containing material, particulate coke, particulate titanium-containing material, chlorine and optionally oxygen or air are fed into a reaction chamber, and a suitable reaction temperature and pressure are maintained. The flow rates of the particulate material, chlorine and chlorine/air or oxygen are adjusted so that the particulate material is maintained in a fluidized state, i.e., it is maintained in a state of suspension and has the appearance of boiling. Gaseous titanium tetrachloride, other metal chlorides, and carbon oxides are exhausted from the reactor chamber. The gaseous titanium tetrachloride so produced can then be separated from the other metal chlorides and used to produce titanium dioxide pigment or titanium metal.
A problem, however, which has not been satisfactorily solved in the foregoing fluidized bed process is that substantial quantities of particulate coke used in process becomes degraded by mechanical action and/or chemical action into fines of less than about 150 microns in size. Such fines generally become entrained in the hot exhaust gases. As a consequence, they have a short residence time in the reaction zone of the process and often exit the reactor in an unreacted state. While the fines can be recycled to the process, they still tend to exit before reacting and therefore generally must be removed from the process. The unreacted fines are therefore a disposal problem and waste of the reductant values in the coke.